Id1 is a member of the DNA-binding protein inhibitors of the bHLH transcription factor family, and locates in the nucleus. It is one of the essential factors for promoting angiogenesis. Id1 has a high expression in most tumors, and a low expression in normal tissues, and therefore is a well established target for antitumor therapeutic strategies, which makes it has been a hot spot in research and development of antineoplastic medicaments to develop an inhibitor with low-toxicity, high efficiency and strong specificity aimed at Id1. At present, it has been reported an antisense oligonucleotide Id1-PCAO specifically targeting endothelial cells and a small molecular cannabidiol inhibiting the expression of Id1 in invasive breast cancer cells. However, none of them is a good candidate for new drug development, since the antisense oligonucleotide as a drug still has many obstacles in technique, while cannabidiol is a cannaboid analogue.
Gastrodia elata BL. is a famous traditional Chinese materia medica, and at present, there is no formal report on a polysaccharide and polysaccharide derivatives thereof. The present inventors extract gastrodia elata polysaccharide from gastrodia elata, and further obtain a sulfated derivative (WSS25) thereof by sulfation of the polysaccharide. WSS25 at a dose of 25 μg/ml can almost completely suppress the expression of Id1 both at mRNA level and at protein level, and therefore can inhibit the growth of tumor by inhibiting the growth of blood vessels while being nearly nontoxic to endothelial cells, and thereby is an Id1 inhibitor having high efficiency and hypotoxicity.